On Fri, 24 Sep 2010 18:18:11 +0530
"Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote:
> From: Andreas Gruenbacher <agruen@xxxxxxx>
>
> Some permission models distinguish between the permission to create a
> non-directory and a directory. Pass this information down to
> inode_permission() as mask flags
>
> Signed-off-by: Andreas Gruenbacher <agruen@xxxxxxx>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> fs/namei.c | 21 ++++++++++++---------
> include/linux/fs.h | 2 ++
> 2 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index b0b8a71..ed786b2 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -253,7 +253,8 @@ int generic_permission(struct inode *inode, int mask,
> * for filesystem access without changing the "normal" uids which
> * are used for other things.
> *
> - * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
> + * When checking for MAY_APPEND, MAY_CREATE_FILE, MAY_CREATE_DIR,
> + * MAY_WRITE must also be set in @mask.
> */
> int inode_permission(struct inode *inode, int mask)
> {
> @@ -1337,13 +1338,15 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
> * 3. We should have write and exec permissions on dir
> * 4. We can't do it if dir is immutable (done in permission())
> */
> -static inline int may_create(struct inode *dir, struct dentry *child)
> +static inline int may_create(struct inode *dir, struct dentry *child, int isdir)
^^^^^
nit: maybe saner as a bool?
> {
> + int mask = isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE;
> +
> if (child->d_inode)
> return -EEXIST;
> if (IS_DEADDIR(dir))
> return -ENOENT;
> - return inode_permission(dir, MAY_WRITE | MAY_EXEC);
> + return inode_permission(dir, MAY_WRITE | MAY_EXEC | mask);
> }
>
> /*
> @@ -1391,7 +1394,7 @@ void unlock_rename(struct dentry *p1, struct dentry *p2)
> int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
> struct nameidata *nd)
> {
> - int error = may_create(dir, dentry);
> + int error = may_create(dir, dentry, 0);
>
> if (error)
> return error;
> @@ -1953,7 +1956,7 @@ EXPORT_SYMBOL_GPL(lookup_create);
>
> int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
> {
> - int error = may_create(dir, dentry);
> + int error = may_create(dir, dentry, 0);
>
> if (error)
> return error;
> @@ -2057,7 +2060,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
>
> int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
> {
> - int error = may_create(dir, dentry);
> + int error = may_create(dir, dentry, 1);
>
> if (error)
> return error;
> @@ -2342,7 +2345,7 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname)
>
> int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
> {
> - int error = may_create(dir, dentry);
> + int error = may_create(dir, dentry, 0);
>
> if (error)
> return error;
> @@ -2415,7 +2418,7 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
> if (!inode)
> return -ENOENT;
>
> - error = may_create(dir, new_dentry);
> + error = may_create(dir, new_dentry, S_ISDIR(inode->i_mode));
^^^^ this is a little
scary, but even if it's
a directory, it'll get
kicked out in a later
check. Would it be
clearer to move up the
S_ISDIR() check in this
function and then pass
this in as false?
> if (error)
> return error;
>
> @@ -2631,7 +2634,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
> return error;
>
> if (!new_dentry->d_inode)
> - error = may_create(new_dir, new_dentry);
> + error = may_create(new_dir, new_dentry, is_dir);
> else
> error = may_delete(new_dir, new_dentry, is_dir);
> if (error)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 26fc8ae..5dc1ebd 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -55,6 +55,8 @@ struct inodes_stat_t {
> #define MAY_ACCESS 16
> #define MAY_OPEN 32
> #define MAY_CHDIR 64
> +#define MAY_CREATE_FILE 128
> +#define MAY_CREATE_DIR 256
>
> /*
> * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
--
Jeff Layton <jlayton@xxxxxxxxxx>
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